n 1 cap : a genus of slender spirally curved rod bacteria of the family Spirillaceae that are gram-negative, microaerophilic, and motile with a characteristic motion resembling a corkscrew, that do not form spores, and that include forms formerly included in the genus Spirillum or Vibrio of which some are pathogenic for domestic animals or humans - see HELICOBACTER 2 : any bacterium of the genus Campylobacter .